Maejo Int. J. Sci. Technol. 2009, 3(03), 371-378
Maejo International Journal of Science and Technology ISSN 1905-7873 Available online at www.mijst.mju.ac.th Full Paper
Nutritive value and nutrient digestibility of ensiled mango byproducts Sompong Sruamsiri * and Pirote Silman Faculty of Animal Science and Technology, Maejo University, Sansai, Chiang Mai, 50290, Thailand * Corresponding author, e-mail:
[email protected] Received: 8 April 2009 / Accepted: 5 October 2009 / Published: 6 October 2009 Abstract: Mango canning by-products (seed and peel) together with ensiled mango peel were subjected to analysis of dry matter (DM), ash, crude protein (CP), crude fibre (CF), ether extract (EE), nitrogen-free extract (NFE), gross energy (GE), neutral detergent fibre (NDF) and acid detergent fibre (ADF). In vitro digestibility of DM (IVDMD), ADF (IVADFD) and NDF (IVNDFD) was determined after digesting the by-products in buffered rumen fluid for 24 or 48 h in an incubator. CP content in peel, seed and peel silage is 4.68, 4.19 and 5.27% respectively. As expected, mango seed has a higher fibre content than mango peel and peel silage as indicated by NDF (53.01 vs 25.87 and 27.56% respectively) and ADF (31.02 vs 19.14 and 17.68% respectively). However, mango seed also has greater GE than mango peel and peel silage (4,070 vs 3,827 and 3,984 kcal/g DM respectively), probably due partly to its high fat content. Four head of male native cattle were used to determine nutrient digestibility of ensiled mango by-products by randomly allowing them to receive ensiled mango peel with rice straw (EMPR) and different levels of Leucaena leaves. Treatments consisted of: 1) ensiled mango peel + rice straw (90:10); 2) ensiled mango peel + rice straw + Leucaena leaves (85:10:5); 3) ensiled mango peel + rice straw + Leucaena leaves (80:10:10); and 4) ensiled mango peel + rice straw + Leucaena leaves (75:10:15). Addition of Leucaena leaves to silage increased apparent digestibility of DM (53.84, 55.43, 59.04 and 58.69% for the four formulations above respectively), probably because of increasing amounts of CP from Leucaena leaves, resulting in greater digestibility of NDF (39.11, 44.47, 47.12 and 43.32% for the four formulations above respectively). Total digestible nutrients (TDN) and digestible energy (DE) showed the same trends as apparent digestibility of DM. Key words: mango by-products, mango peel, mango seed, apparent digestibility, energy value
372 Maejo Int. J. Sci. Technol. 2009, 3(03), 371-378 Introduction Mango is considered as one of the most delicious fruits in Thailand. Its harvesting time is between January and May, which is in the dry season when green forage is in shortage. Mango is an excellent source of vitamin A and C, as well as a good source of potassium, beta-carotene and fibre. Normally, it is produced for human consumption as raw or ripe mango products. During the processing of ripe mango, its peel and seed are generated as waste, which is approximately 40-50 % of the total fruit weight. Mango peel is a good source of dietary fibre and its chemical composition may be comparable to that of citrus fibre. The peel has a high value of antioxidant activity and glucose retardation index while its aroma and flavour is pleasant [1]. The peel is thus palatable to cattle but very few farmers use it for animal feed because of the high moisture and acidity content. During the processing of ripe mango, the waste (peel and seed) is a problem for canning factories. Its disposal may appreciably increase environmental pollution due to its rapid decay, thus becoming a good source of house fly multiplication. However, Omole et al. [2], Govinda Naik et al. [3] and Naveen et al. [4] reported that fruit waste and by-products may be used as alternative feed in livestock rations either as dry product or as silage. Therefore, the ensiling of mango by-products especially mango peel may be an economical way to reduce the problem of waste disposal from mango production as well as increase their utilisation as animal feed. To produce good silage from mango peel, it would be desirable to mix it with dry materials such as rice straw to adjust moisture and with Leucaena leaves to increase protein content for proper fermentation of the ensiled products. This study was conducted to determine the nutritive value of mango by-products and evaluate the digestible nutrients of ensiled mango by-products with rice straw and Leucaena leaves (Figure 1). The feed could possibly be used to set up a feeding strategy for Thai native beef cattle fed with low quality roughage. Materials and Methods Composition Ripe mango (Mangifera indica) by-products were obtained from a cannery plant in Sarapee district, Chiang Mai province. The by-products were dried on the truck overnight before ensiling and sampling for analysis. Peel and seed were hand- separated and the separated products were mixed thoroughly. Random samples of peel and seed were taken for analysis of dry matter (DM), ash, crude protein (CP), crude fibre (CF), ether extract (EE), nitrogen free extract (NFE) and gross energy (GE) according to the methods described in AOAC [5]. Organic matter (OM) was calculated from DM (OM =DM – ash). The analysis of neutral detergent fibre (NDF) and acid detergent fibre (ADF) was carried out according to the methods of Goering and Van Soest [6].
373 Maejo Int. J. Sci. Technol. 2009, 3(03), 371-378
mango peel
EMPR+0%LL (peel : rice straw =90:10)
EMPR+10%LL (peel : rice straw: LL=80:10 :10)
mango seed
EMPR+5%LL (peel : rice straw : LL=85:10:5)
EMPR+15%LL (peel : rice straw: LL=75:10 :15)
Figure 1. By-products from mango and ensiled mango by-products In vitro digestibility In vitro digestibility of DM (IVDMD), NDF (IVNDFD) and ADF (IVADFD) of mango peel, mango seed and mango peel silage was determined using ANCOMII Daisy Incubators (ANKOM Technology, Macedon, NY). Samples were ground (1mm) and incubated in buffered rumen fluid for 24 h and 48 h. Rumen fluid was obtained from 2 fistulated native bulls before ad libitum feeding with guinea grass. The experimental design was Completely Randomised Design.
374 Maejo Int. J. Sci. Technol. 2009, 3(03), 371-378 Apparent digestibility Four head of male native beef cattle at four years of age with average body weight of 236 + 13.3 kg were randomly allocated to one of the four dietary treatments according to Latin Square Design. The treatments consisted of (1) 90:10 ensiled mango peel + rice straw (EMPR, 90:10), (2) 85:10:5 ensiled mango peel + rice straw + Leucaena leaves (EMPR+5%LL=85:10:5), (3) 80:10:10 ensiled mango peel + rice straw + Leucaena leaves (EMPR+10%LL= 80:10:10), and (4) 75:10:15 ensiled mango peel + rice straw + Leucaena leaves (EMPR+15%LL= 75:10:15). The diets were fed to the animal twice daily at 2.0 % of the body weight (DM basis). Water and mineral blocks were freely available throughout the experimental periods. Total collection method was assigned for the determination of apparent total tract digestibility of nutrients. The experiment was conducted at Maejo University during July - October 2008. The experiment consisted of four periods with each digestibility period lasting 19 days and preliminary period taking place in the first 14 days while collection period was in the last 5 days. Feed intake was recorded daily throughout the entire experiment. Dietary DM intake was calculated on DM basis. Feed, feces and leftover feed were individually collected and used for the calculation of nutrient digestibility. Total digestible nutrients (TDN) were calculated using the equation: TDN = digestible CP + digestible CF + digestible NFE + digestible EE 2.25 [7]. Gross energy of feed and feces was determined using an adiabatic bomb calorimetre (IKA calorimetre system C 5000). Digestible energy was then calculated. The data were analysed according to 4x4 Latin Square Design [8]. The significant differences between treatments were analysed based on Duncan’s new multiple range test [9].
Results and Discussion Composition The composition of ripe mango by-products are shown in Table 1. The dry matter content of mango peel was lower than that of mango seed. At present the price (0.20 Baht per kg) of mango byproducts may be economical as a source of roughage, even though their CP content is low. Crude protein content of mango peel in this experiment (4.68%) was lower than the value reported by Ojokoh (8.64%) [10], but higher than that reported by Naveen et al. (3.9%) [4] and Buwjoom and Maneewan.(3.18%) [11]. This might be due to differences in varieties, cultivation and method of byproduct collection. However, mango peel in this experiment was higher in CP and NFE (4.68 and 76.13% of DM) but lower in CF and ADF (10.10 and 19.14 % of DM), when compared to mango seed. Mango seed was higher in GE and CF, mainly because the kernel is usually a good source of starch, fat and protein. This agreed with Elegbede et al [12] who reported that mango kernel was high in fat and starch (12.8 and 32.8% respectively).
375 Maejo Int. J. Sci. Technol. 2009, 3(03), 371-378 Table 1. Composition of ripe mango by-products By-product Mango peel Mango seed Ensiled mango peel
DM (%)
CP
CF
20.10 23.88 18.27
4.68 4.19 5.27
10.10 30.84 9.02
% of DM EE NFE
NDF
ADF
GE (kcal/g DM)
1.21 2.72 1.63
25.87 53.01 27.56
19.14 31.20 17.68
3,827 4,070 3,984
76.13 47.79 75.87
Ensiled mango peel was highest in CP but lower in CF and ADF. This might be due to the fact that during fermentation process carbohydrates including cellulose, pectin, lignocellulose, starch and sugar are broken down by microorganisms to produce microbial biomass, and therefore the fibre content decreased but CP content increased. Results from this experiment agreed with those of Ojokoh [10], who reported that fermentation of mango peel increased protein content of the fermented product while there was a decrease in fibre content. In vitro digestibility Compared with mango seed, mango peel and mango peel silage were higher in IVDMD, IVNDFD and IVADFD at 24 h and 48 h (Tables 2-3). However, the in vitro digestibility of DM, ADF and NDF in mango seed suggests that it might be acceptable for feeding ruminants if it was ground, as performed for this laboratory analysis. The high NDF (53.01%, Table 1) of the hard outer shell is compensated by the highly digestible, high energy content inside the shell. Feeding trials are needed to determine if ground mango seed is acceptable as ruminant feed. Also, methods for separation of the seed shell from the kernel should be investigated. Table 2. In vitro DM and fibre digestibility (%) of mango by-products at 24 h Item IVDMD** IVNDFD** A Mango peel 69.28 ± 2.3 40.63B ± 1.8 Mango seed 55.77 B ± 1.9 36.24C ± 1.6 A Mango peel silage 74.11 ± 2.1 48.33A ± 2.1 * Means with different superscripts significantly differ (P
